(1) Field of the Invention
Percutaneous transluminal angioplasty (PTA) procedures can treat arterial disease. In such endovascular procedures, cutting balloons are sometimes considered as a treatment option for opening blocked coronary and peripheral vessels. Such balloons are sometimes configured so that balloon pressure is communicated to one or more cutting elements. Those elements may selectively cut stenosed vessel walls. In the hands of a skilled interventionist, PTA atherectomy procedures have sometimes reduced vessel recoil, lessened vessel tears and may have improved outcomes in comparison to traditional PTCA procedures.
Severing elements used in such balloons can for analysis be said to include an effective surface feature (e.g., an edge) that is capable of incising or scoring vessel walls with which they come into contact. But if suitable precautions are not taken, the incising elements can tear, cut or perforate the thin, fragile inflation balloon during assembly, handling or use. It is also possible that an unintended balloon rupture could damage the arterial wall. This may result in loss of inflation fluid into the patient's vasculature. Another problem may arise if an inadvertent or unwanted cutting occurs of adjacent perhaps healthy tissue as the cutting balloon is being positioned or withdrawn from the vasculature.
(2) Description of Related Art
A device with a cutting edge which is covered within the pleats of an expandable clover leaf-shaped tube is disclosed by Shiber in U.S. Publication No. US 2002/0151924. However, such designs may fail to protect a fragile balloon during installation of the cutting edges, even before the device is used in situ. In addition, because the blades are situated within the balloon folds, creased portions of the balloon may be exposed to the blades when the device is navigated by twisting, turning and bending through narrow tortuous vasculature passageways.
The following references, among others, were considered before filing this application: U.S. Pat. Nos. 7,686,824; 7,799,043; and 7,691,080.